From what I have read of the Kindle Fire Silk Web Browser it appears it will be very fast and enhanced by Amazon's own servers.

Whether or not the Silk web browser is fast has yet to be seen. (What is considered "fast" seems to be beaten by every new release.) However, the Silk technology will probably not be good for online games; without putting too much thought into it, I'm guessing it will actually be worse for games excepting the initial page load. Silk is excellent for non-optimized web pages where you are loading a lot of items (especially deeply "nested" items), but your game isn't likely to fall into either of those categories.

As gweminence mentions, if it is Flash, then Silk isn't likely to help at all. From personal experience, Flash is functional on mobile devices, but too many Flash developers assume the use of a pointing device (which most tablets lack) and moving around when using larger-than-screen Flash objects is almost impossible.